This invention relates to novel couplers for use in hair coloring compositions comprising one or more oxidative hair coloring agents in combination with one or more oxidizing agents. The invention also relates to hair coloring compositions of these novel couplers and to coloring or dyeing of hair using compositions containing these couplers.
Coloration of hair is a procedure practiced from antiquity employing a variety of means. In modern times, the most extensively used method employed to color hair is to color hair by an oxidative dyeing process employing hair coloring systems utilizing one or more oxidative hair coloring agents in combination with one or more oxidizing agents.
Most commonly a peroxy oxidizing agent is used in combination with one or more oxidative hair coloring agents, generally small molecules capable of diffusing into hair and comprising one or more primary intermediates and one or more couplers. In this procedure, a peroxide material, such as hydrogen peroxide, is employed to activate the small molecules of primary intermediates so that they react with couplers to form larger sized compounds in the hair shaft to color the hair in a variety of shades and colors.
A wide variety of primary intermediates and couplers have been employed in such oxidative hair coloring systems and compositions. Among the primary intermediates employed there may be mentioned p-phenylenediamine, p-toluenediamine, p-aminophenol, 4-amino-3-methylphenol, and as couplers there may be mentioned resorcinol, 2-methylresorcinol, 3-aminophenol, and 5-amino-2-methylphenol. A majority of the shades have been produced with dyes based on p-phenylenediamine.
For providing a blue coloration to hair, m-phenylenediamine has been extensively used in combination with p-phenylenediamine as a primary intermediate. However, the resulting blue dyes undergo intramolecular cyclization to form red 2,8-diaminophenazine. This conversion has been suggested to be responsible for fading to red in hair (warm wearing or red fading). The rate of the cyclization depends upon positions of the substituents and can be decreased by the use of m-phenylenediamine with an electron-donating substituent such as an alkoxy group. Because of the color change over a period of time, there is a need for new blue couplers for use in oxidative hair dyeing compositions and systems.
This invention provides novel couplers of the formula (1): 
wherein Y is selected from CH or N and Z is selected from H, OCH3, NH2 and alkyl of from 1 to 4 carbon atoms, with the proviso that when Y is N the 2,4-diaminophenoxy moieties are positioned at the 4 and 6 positions on the pyrimidine ring.
These novel couplers are used to provide coloration to hair in which there is good dye uptake by the hair and provides shades or colors which are stable over a relatively long period of time. The novel couplers provide for dyeing of hair that provides color or shades that possess good wash fastness, good selectivity, and do not undergo significant changes on exposure to light, perspiration or shampooing.
The coupler compounds of this invention are those of formula (1) 
wherein Y is selected from CH or N and Z is selected from H, OCH3, NH2 and alkyl of from 1 to 4 carbon atoms, with the proviso that when Y is N the 2,4-diaminophenoxy moieties are positioned at the 4 and 6 positions on the pyrimidine ring.
Preferably, Y is CH or N and Z is H, OCH3 or and CH3.
Especially preferred couplers of this invention are the following compounds:
4-{[2-(2,4-diaminophenoxy)pyridin-3-yl]oxy}benzene-1,3-diamine;
4-{[2-(2,4-diaminophenoxy)pyridin-4-yl]oxy}benzene-1,3-diamine;
4-{[2-(2,4-diaminophenoxy)-4-methoxy-pyridin-6-yl]oxy}benzene-1,3-diamine;
4-{[6-(2,4-diaminophenoxy)pyrimidin-4-yl]oxy}benzene-1,3-diamine;
4-{[6-(2,4-diaminophenoxy)-2-methyl-pyrimidin-4-yl]oxy}benzene-1,3-diamine; and
4-{[6-(2,4-diaminophenoxy)-5-methoxy-pyrimidin-4-yl]oxy}benzene-1,3-diamine.
The novel coupler compounds of formula (1) of this invention are readily prepared according to the following reaction sequence wherein: Y and Z are as defined hereinbefore; W is OH when Y is CH and is halogen selected from Cl, Br or F when Y is N, and R is OH when Y is N and is halogen selected from Cl, Br or F when Y is CH, with the proviso that when Y is N the W""s are at the 4 and 6 positions on the pyrimidine ring. 
In this synthesis, when Y is CH, a compound of formula (2) wherein the W""s are each OH is reacted with a 2,4-dinitro-halobenzene, preferably 2,4-dinitro-fluorobenzene, in the presence of potassium carbonate to produce a compound of formula (3). Hydrogenation of the compound of formula (3) with Pd/C under hydrogen pressure produces a compound of formula (1) where Y is CH.
In this synthesis, when Y is N, a compound of formula (2), wherein the W""s are halogen attached at the 4 and 6 positions on the pyrimidine ring, is reacted with 2,4-dinitrophenol to produce a compound of formula (3) wherein the 2,4-dinitrophenoxy moieties are attached to the pyrimidine ring at the 4 and 6 positions of the pyrimidine ring. Hydrogenation of such a compound of formula (3) with Pd/C under hydrogen pressure produces a compound of formula (1) wherein Y is N and the 2,4-diaminophenoxy moieties are attached to the pyrimidine ring at the 4 and 6 positions of the pyrimidine ring.